Several solutions for implementing a toll collecting system have been proposed in the prior art. Thus, for example, systems were proposed wherein a toll card can be purchased at monitoring stations located at state, region or zone boundaries, said card entitling the purchaser to use the desired road section. The toll card is usually taken from a machine at an entry station of a particular tolled road section, and the toll fee, which is calculated by way of a respective calculation key, is paid at an exit station by the vehicle driver either in cash or by means of a credit card.
Similarly, a separate monitoring station with its own entry lane can be provided for commuters or vehicle drivers who frequently use a particular stretch of road, the vehicle being identified at said monitoring station by way of optoelectronic license plate recognition, and the vehicle driver, assuming a corresponding entry is present in a user database, being allowed to pass at a toll barrier. The toll charge due is either paid as a lump sum or debited in several installments over a year from the toll user's account.
Also possible is a localization of the vehicles of toll users via toll portals or monitoring units which are based on microwave communication. An electronic toll system of this type has been realized in Austria, for example, in order to enable vehicles having a total weight of 3.5 tonnes or more to be tolled automatically. For this purpose toll portals are erected on all tollable road sections of the national trunk road network, which is to say, in the case of Austria, motorways and expressways, which toll portals are equipped with microwave antennas and communicate with the mobile detection units which are installed in the vehicles and which every vehicle liable to pay tolls must carry.
However, flexibly regulated toll collecting methods are becoming increasingly important not just for private passenger vehicle traffic, but more particularly also for truck traffic. For this purpose a mobile detection unit known as an “on-board unit” and referred to in the following as a position determining unit is being used throughout Europe. Said unit is a device which is installed in the truck or vehicle in order to allow automatic billing of toll charges in a charge collection or toll system. German, French, Italian and Spanish motorway operators, but also increasingly other countries inside and outside Europe, are turning to position determining units of this type in order to register toll charges.
In systems of this kind an electronic mobile detection unit is assigned to a specific vehicle. A detection unit of this kind is about the size of a car radio and can usually be installed in the standardized receiving slot for car radios or mounted on the dashboard of the driver compartment. The sections of tolled roads that have actually been used by the toll user and attract a charge can be ascertained by means of different navigation systems which operate in cooperation with the detection unit. The use of satellite positioning systems, for example, is common, the GPS (“Global Positioning System”) system operated by the United States Department of Defense currently experiencing the most widespread use among navigation applications. By means of GPS or an equivalent positioning system, the position of a receiver can be determined worldwide at any time with a spatial resolution of less than 10 m. By providing certain add-on modules such as, say, DGPS (“Differential Global Positioning System”), in which correction data for a mobile receiver is calculated with the aid of the position data of a stationary base receiver, it is even possible to pinpoint the position of a vehicle exactly with a spatial resolution of less than 1 m.
In this case individually tailored software components ensure an appropriate linking of the received geographical position data of the respective vehicle of the toll user with stored information relating to tolled road sections in the form of electronic images of the entire road network, and determine the sum total of the collected toll values, which are transmitted for billing purposes at periodic intervals. Time data, i.e. periods of time which the vehicle spends in a particular toll zone, can of course also be taken into account in toll calculation algorithms.
In reality, this can be effected for example by overlaying the electronic image of roads that are subject to tolls within a road network with detection zones. In this case said zones are geometric figures such as, say, circles, tubular areas or closed polylines (n corners) which are defined by means of geographical position data and supplementary data such as, say, the diameter in the case of a circular detection zone. During the journey of a tollable vehicle, the position determining unit disposed in said vehicle constantly determines the position data of the vehicle. Said position data is transferred into the electronic image of the road network and compared with the detection zones. If the vehicle enters a detection zone during its journey, the position data lying within the detection zone is stored until the vehicle leaves the detection zone again. The position data within the detection zone can subsequently be used as a basis for calculating the total number of kilometers traveled in the tollable zone, and said total used, possibly in conjunction with vehicle-related data such as, say, total weight, or road-section-related data such as, say, different toll levels, for calculating the toll.
When the toll system is configured, effort is naturally focused on detecting tollable journeys as accurately as possible. For this reason the detection zones are chosen as small as possible in order to avoid incorrectly detecting vehicles which, although moving in very close physical proximity to tollable zones, are not actually traveling on tollable roads. In this case the detection zones should record the road-section-related course of tollable roads as accurately as possible. However, the lower limit for the size of the detection zones is set by the spatial resolution of the position determination means of a vehicle, as well as by deviations of the electronic image of the road network from the real state of affairs. Furthermore, the accuracy of the transfer of the vehicle position into the electronic image of the road network is also subject to limits due to other factors which often can only be recognized as a result of practical experience. In spite of careful specification of a detection zone it can therefore happen during practical operation of the toll system that a vehicle travels on a tollable road without being detected by the toll system, since the corresponding detection zone is not optimally specified. However, whether a detection zone is optimally specified can again often only be ascertained during practical operation, and moreover by those journeys which have actually passed through a detection zone, but have not been detected due to suboptimal choice of the detection zone. However, it is precisely these journeys which are not detected by a toll system according to the prior art. Owing to the large volumes of data, however, it is not feasible to carry out a retrospective check of all journeys based on a comparison of the position data with the detection zones.
DE 4344433 describes “entry and exit coordinate vectors” with which the location coordinates of the vehicle are correlated. However, if said “entry and exit coordinate vectors” are wrongly adjusted, and consequently vehicles constantly fail to be detected despite being in the tollable area, or vehicles are incorrectly detected even though they are outside the toll area, there is no means of making a retrospective adjustment.
In WO 95/20801 reference is made to “collecting points” at which vehicles are detected. Given “agreement” of the vehicle position with the position of a collecting point the passing of the vehicle is detected. However, there is no means of constantly checking the positioning of the collecting points, which are defined by “predetermined geographical positions”, and making possible corrections that are necessary. If, for example, a collecting point is wrongly chosen, or systematic measurement errors in the position determination of the vehicle occur in this area, deficiencies in the collecting of the toll levy constantly take place which, according to WO 95/20801, cannot be detected.